1. Democracy. The Constitution begins 'We the People of the United States', showing right from the get go that the US is run by The People. It's We The People who ordained the Constitution, make it legitimate, etc. The Constitution is clearly about one man/one vote, representatives elected by the people of each state, the president elected by delegates elected by the people. Originally Senators were elected by state legislatures, but they are elected directly now.
And originally, the idea of who could vote was much more restrictive. Several amendments have widened the classification of 'voter'. People who used to be slaves, and women, in particular, have been added.
2. Equality. The Constitution, and 'The American Way' allows for only one level of citizenship. ALL citizens (supposedly) have exactly the same rights and privileges under law. Anyway, that's the idea. In practice it doesn't always work that way. Again we've needed amendments to force states to accept blacks, naturalized citizens, etc., as full citizens.
3. Freedom. This is the most subjective since everyone has a little different idea of freedom. Some people think 'freedom' means the right to carry a gun around wherever they want. But in reality our freedoms are protected by all the rest of the Bill of Rights. Freedom (to me) means you can't be arrested or punished unless it can be proven you did something wrong. You have the right to defend yourself, the right not to incriminate yourself, etc. Beyond that, we have the freedom to move around the country, pick a career, live wherever we want, work at any job where we can be hired, and basically to live our life with only as much govt. interference as necessary.
4. Opportunity. All these things are connected. Opportunity is a form of freedom. It means that everyone can get a good education regardless of their parents' ability to pay. And that someone can rise as high in life as he is able, despite the place he was born or the condition of his family. Again, this is an ideal, in practice it doesn't always work out. Opportunity and what we call 'social mobility' is driven by education, and there are forces in the US that are trying to destroy public education so their own children will have an advantage over kids born poorer.
5. Rights. Also related to the 'classless' society. Everyone has the same rights, including police and fire protection, use of public resources like roads and bridges and parks, freedom from persecution, the right to vote, to dissent and protest, to believe as they please, etc. etc.
